NEW YORK/WASHINGTON (Reuters) – A data center critical for allowing uninsured Americans to buy health coverage under President Barack Obama’s healthcare law went down on Sunday, the U.S. government said, in the latest problem for the “Obamacare” rollout.

Verizon’s Terremark operates the data center behind a federal system for determining eligibility for government subsidies to buy insurance nationwide and hosts HealthCare.gov, the website that makes insurance available in 36 of the 50 states.

The data center experienced a failure on Sunday that led it to lose network connectivity, Health and Human Services Department spokeswoman Joanne Peters said.

Online insurance exchanges opened on October 1 under the law to offer health insurance plans to millions of uninsured Americans. But it has been marred by technical glitches and delays as would-be customers encounter error messages and long waits, often failing to make it through the system despite repeated tries.

“We are working with Terremark to get their timeline for addressing the issue,” Peters said in an email. “We understand that this issue is affecting other customers in addition to HealthCare.gov, and Terremark is working (to) resolve the issue as quickly as possible.”

Peters said the newest glitch also affected a data services hub – an electronic traffic roundabout that connects numerous federal agencies and can verify people’s identity, citizenship, and other facts.

Problems with the data services hub affect customers of both HealthCare.gov and the state-run exchanges. State exchanges had been running smoothly.

The verification is necessary to determine eligibility for tax credits that reduce the cost of monthly insurance premiums, a key provision of the law.

A spokesman for Verizon said the problem would be fixed “as soon as possible.”

“Our engineers have been working with HHS and other technology companies to identify and address the root cause of the issue,” Verizon spokesman Jeff Nelson said.

Health officials in Connecticut, one of the 14 states, plus the District of Columbia, that launched their own health exchanges instead of relying on federal government sites, said on Sunday that potential customers would not be able to complete the sign-up process for some services but could create accounts and search for pricing comparisons.

The U.S. Centers for Medicare and Medicaid Services told Connecticut officials about the outage and gave no indication of when the data services hub would be functioning again, said a spokeswoman for Access Health CT, the Connecticut exchange.

The problems with the rollout of the law have become a political liability for Obama. The White House has said Obama still has “full confidence” in HHS Secretary Kathleen Sebelius, whose department is responsible for implementing the law. Sebelius has faced Republicans calls for her resignation.

(Reporting by Sharon Begley and David Morgan,; Writing by Anna Yukhananov and Emily Stephenson; Editing by Christopher Wilson and Will Dunham)